What about Life?

What is the definition of life? That was the question I came across while watching TV today. It was a program where a man is trying to sell some encyclopedias to a school teacher and the teacher asks, 'Does it say what is life?'
At this point, I thought to myself, it is what you think it is. There is no real definition of life, though if you search it on the Internet, the answer is 42. Life is a matter of perspectives, the angle that you as an individual sees it. I may see life as enjoyable and precious, yet there are some people out there who sees it as tough. But then it leads to the question: What is the main purpose of life?
Let's not look at it from a religious point of view. I've yet to reach the point where I find my purpose. But for now, all I can ever ask myself and the world, what's the point of having obstacles to make us tougher in life when it is okay to not have any challenges in our life and be tougher when we don't need that toughness? Remember, I'm still learning, so I may give a child point of view most of the time.